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Publisher/Editor: I. D. Cheek. Sr. aka Or. kigormtis_ _ V2hS: March, 1992 


A Journal of VHF-UHF Scanner Technology S Engineering 

Published at: COHHtronics Engineering; PO BOX 262478: San Diego, CA 92196 Copyright (c) 1991-2 (All Rights Reserved) 04.00 


A heavy workload fraught with problems galore and with 
enumerable distractions resulted in the WSR going to 
press late this month. Please accept my apology and 
sincere efforts to not let it happen very often. For the 
future, let me restate our minimum guarantee of 8-pages 
per issue and 10-issues per year. Given our small size 
and an ever present need to earn the bread & butter, it 
is conceivable that the WSR might not go to press for a 
given scheduled month. If this should ever be the case, 
we'll simply give up our scheduled bi-month issue of 
May-June or Nov-Dec. The bottom line is that a minimum 
of 40-pages and five issues will be released each half 
year, or an appropriate auto-extension made to affected 
subscriptions sufficient to meet the minimum subscription 
guarantee. As it is, we try to exceed the minimum for 
most issues. The point here is that if you should miss 
an issue, relax and don't panic; more than likely it will 
either be late OR made up in a bi-month issue. Obviously, 
as we grow, we’ll have to become more rigid in scheduling 
and planning, and we are preparing for growth right now! 


We have a rigid and arduous schedule that does not afford 
hobby-related chit-chat by phone. Given the nature of my 
work: writing and technical labor, I can ill afford to be 
unpredictably distracted & jolted out of focus like the 
telephone can do. Distraction & lack of focus cause 
inferior products. I am loathe to pass off anything less 
than my very best. So, it's difficult & almost impossible 
for me to be available by telephone. Client business is 
not included in this policy, but since I come and go at 
all hours, the telephone is just not the BEST for me. I 
have long supported MAIL as the best medium of routine 
communications. I go overboard to answer all mail, but 
even that has become time consuming. So I have devised 
another and very unique forum for hobby, business or most 
any other need to get in touch with me: a Computer 
Bulletin Board, BBS, known as the Hertzian Intercept! 

Midnite- 6:00am, Pacific Time: (619) 578-9247 

Effective immediately, you can reach my BBS daily between 
the hours of midnight - 6:00 am, Pacific times. The phone 
number is (619) 578-9247 for ONLY the stated hours. At 
other times, this number is for business ONLY and is 
connected to an answering service. First time callers to 
the BBS have 20-mins to answer the easy log-on questions 
and to leave a personal and/or' introductory message. You 
won’t have many privileges for the first session, but 
approval & upgrade of your security status will normally 
be made within 24 hours, after which you'll have 60-mi ns 

per day and access to most of the message and file areas. 

To access my Hertzian Intercept B8S, you need a computer, 
a modem and a telecom or terminal program that is capable 
of running the modem to communicate with other computers 
via telephone lines. The parameters of my BBS are: 2400, 
1200 & 300 baud; 8 data bits; 0 parity, and 1 stop bit 
(8N1). When you call the BBS during its active hours my 
computer will answer with a CONNECT message followed by a 
message saying "Press Escape Twice to Enter the BBS". Do 
so and wait 30-sec for the BBS to load after which you'll 
be greeted with the name of the BBS and a short list of 
questions, mostly technical so my BBS can match the needs 
of your computer. After you've completed the 
questionnaire and selected a password, you'll be accepted 
for 20-mins of limited operations. At that point and if 
I were you, I would go straight to the (H)essage area 
from the Main Menu and leave me a message. You can snoop 
around later if there's time. So press (M) to start the 
message base and at the prompt, select (A)rea followed by 
a (6) for E-Mail to SysOp. Then select (P)ost A Message 
at the next menu, whereupon you'll see a message form 
with your name in the FROM: line. Enter SYSOP or my name 
(Bill Cheek) on the TO: line, followed by one or two 
words for the subject of your message. (Hello; Question; 
Business; Help; etc). Then answer (Y)es or (H)o to 
Change Anything? after which you'll be presented with a 
message screen. Write your message, and when completed, 
punch your ENTER, RETURN or Carriage Return key once or 
twice to prompt the self-explanatory menu. If all is 
well, press (S)ave your message. You can then look 
around the BBS for the remaining time left. 

One quick way to leave me a message after answering the 
questionnaire is to press (L)og Off which will take you 
to the closing menu. Select (L)eave Message to SysOp 
First which will accomplish the same thing as above, 
except that after you’ve saved your message, you'll be 
automatically disconnected. It is quick and efficient 
that way, however. Unless I am out of town or sick, I 
will answer all messages left in either manner within 
24-hours. When you call back, you'll see where there is 
"mail in your mailbox". Using this BBS is relatively 
intuitive and not at all difficult. Even if you are a 
greenhorn at computer networking, give it a try. 

I am a greenhorn too, and not at all a BBS expert. Since 
the Hertzian Intercept is so new and I am so green, you 
won’t find a huge library of files or message bases, but 
you will find information and a pleasant roundtable which 
will grow with time. You will find this a quick, neat 
and timely way to communicate with me, whether your need 
is business, hobby or just to get acquainted. There will 
also be others there who share our interests in radio! 

INTERFACE BBS 24-HRS/DAY: (619) 297-7733 


NOTE FOR URGENT NEEDS! My BBS will be part-time until I 
can get a 3rd phone line put in, which will be another 
2-3 months. If my part time hours of midnight to 6:00am 
are not convenient, there is a local full-time BBS to 
which mine is linked. You can call the INTERFACE BBS at 
(619) 297-7733 which operates very much like mine as 
described. After you've logged on, go to the MESSAGE 
BASE similar to above and select under AREAS, either the 
San Diego Scanner Conference, or the San Diego Shortwave 
Conference, both of which are direct linked to my BBS. 
While these two conferences are public, I receive any 
messages left there several times per day. Address any 
messages to me as: Bill Cheek. Likewise, any messages I 
post there will be available at the INTERFACE BBS several 
times a day, which like I said, is open 24-hours a day. 

My Hertzian Intercept BBS is a member of the FidoNet, my 
address of which is 1:202/719.2 so if you are affiliated 
with any local FidoNet BBS's in your area, we can send & 
receive semi-private NetMail via that medium as well as 
public messages on the Shortwave/Scanner Echo. I am also 
on the GEnie Information Service, address "N.CHEEKSR.1". 



E-Systems Melpar Div introduced CELLTAP, a versatile, 
compact cellular radio monitoring system, in July at the 
National Technical Investigators' Association exhibition 
held in Washington, D.C. 

Designed for law enforcement professionals, the CELLTAP 
system is a compact dialed number recorder and monitoring 
system, which can be used at a fixed location or as a 
battery-powered portable unit. CELLTAP is intended for 
monitoring and recording cellular telephone signaling 
activity (such as off-hook, on-hook, and dialed numbers) 
and for monitoring or recording audio. The CELLTAP 
system can exploit multiple cellular channels with 
additional PC expansion cards & receivers. 

The software supplied with the CELLTAP system provides 
user-friendly operation with menu and function key driven 
commands. The data collected by the system is stored on 
the PC compatible computer's hard disk drive, along with 
the time and date in a format appropriate for standard 
data base programs. The standard format allows data to 
be sorted & analyzed, and then, using the resulting data, 
provides the means for an operator-generated report. 

The compact size of CELLTAP allows a number of packaging 
options. For example, a 2-channel system that includes a 
notebook style PC and microcassette recorders fits in a 
standard 5-inch briefcase, while a 16-channel system 
occupies just 17.5 inches of rack space. 

EDITOR'S NOTE: The price of a basic CELLTAP system 
without a computer is around $2,500. Now see the next 
article for a cellular decoder that's well under $200! 

Cellular Mobile Telephone control channel and voice 
channel data can now be economically detected, decoded & 
displayed with most any kind of a computer that has a 
serial port capable of 9600 baud! Decode continuous data 
from a control channel as well those "bzzzt's" on the 
voice channels: hand-off freqs, power changes, phone 
numbers & more! The Digital Data Interpreter (DDI) from 
CCS of Milwaukee, Wl, comes as a kit of parts containing 
a professionally produced & etched printed circuit board 
and all parts to mount thereon. The user provides only a 
project box in which to install the completed board; 1C 
sockets (recommended but not essential); a power supply 
or DC Adaptor and a serial communications cable with a 
DB-9 connector on one end for the DDI and an appropriate 
DB-9 or DB-25 to match the serial output connector of the 
computer. A modem is not necessary but a telecom or 
terminal program is required to read, display and store 
the decoded cellular data in the computer. A capture 
buffer can record and store decoded data for future use. 
Such programs include TELIX, PROCOMM, EASYCOM, 121, ASCII 
EXPRESS, TO TELECOM, DATALINK, and many, many more. 

The DDI connects to a scanner or other cellular receiver 
with ease via a mini coax or shielded mic cable. The 
shield of the cable goes to receiver ground while the 
center conductor connects via a 1-uF capacitor to the 
"high" lug of the SQUELCH control in most scanners; 
otherwise to the audio output pin of the receiver's NFM 
Discriminator chip. The "high” lug of the SQUELCH is 
eminently suitable for the PRO-2004/5/6, PRO-34/37 and 
PRO-2022, and should also be just fine for most other 
scanners. CCS suggests using the EXT SPKR jack for AOR 
scanners, specifically the AR-2500 which was the test bed 
for the DDI. This is worthless in Realistic scanners for 
good reason! The PRO scanners have built-in voice-band 
filters in the audio sections which serves to limit out- 
of-voice band signals, including CTCSS tones and high 
baud rate data signals! Apparently, AOR scanners are not 
so well filtered. CCS is investigating this matter of 
best installation points and should have current findings 
available at time of order or inquiry for information. 

The DDI requires two wires for 12-v DC power; two wires 
for connection to the scanner and a 9-conductor serial 
cable to most any kind of computer with a serial or COMM 
port. The DDI runs at 9600 baud, 8-data bits, 0 or no 
parity and 1 stop bit (8N1). Assembly of the DDI's PCB 
is not difficult, maybe requiring a couple of hours or 
so if all parts and materials are on hand. Don't be 
concerned about mounting the PCB in a project box until 
it has been checked and operated for a while to ensure 
proper operation. Most any DC Adaptor rated at 12-volts 
@ 100-ma or more will suffice for power needs. 

Operation of the DDI is routine, though mastering the 
control codes will take a little time. Control of the 
DDI is exclusively from the computer's keyboard. The 
Operating Guide could be better and more explanatory, but 
a little practice will make most aspects perfectly clear. 

"THE WORLD SCANNER REPORT" (c) 1991-2; V2N3 - March, 1992; Page 2 

The DDI has many modes and variances of operation, but 
two main or basic modes; control channel data and voice 
channel data. It may not be widely known that short data 
bursts are sent on voice channels to control some aspects 
of the mobile telephone, among these are the handed-off 
freqs, power level control, ID & registration codes & 
more. Every so often, a short "bzzzt" will be heard on 
cellular voice channels. These are the data bursts, 
whereas on the control channels, there is almost a 
continuous stream of data, too lengthy and varied to 
discuss here. Suffice it to say for now that the DDI can 
fill a screen with decoded data from a busy control 
channel so fast that it can't be read as the data scrolls 
off the screen in a continuous stream. One of the more 
pertinent uses of the DDI is to find the new frequency 
when a cellular conversation is "handed off”. Law 
enforcement personnel will appreciate this capability 
when a drug dealer is about to announce the drop point as 
a frequency hand-off takes place. The new frequency is 
decoded from that momentary "bzzzt" and displayed on the 
computer’s monitor. As soon as that channel goes dead, 
reprogram the scanner with the indicated frequency to 
resume unabated monitoring. 

The Digital Data Interpreter Kit and instructions are 
available from: CCS; PO Box 11191; Milwaukee, HI 53211 

CAVEAT: The ECPA of 1986 makes it unlawful to intercept 
cellular telephone conversations including computer data 
communications, so the DDI probably can be used legally 
only by authorized law enforcement, telephone industry 
and maintenance personnel. Check with an attorney if in 
doubt about the legality of your application. 


by Perry Joseph, President, DataFile Inc. 

About the Author: Perry Joseph is a programmer who 
specializes in custom database applications. His company, 
DataFile, Inc., has recently introduced a frequency 
management system for IBM and compatible computers. (See 
V1N9P8). In a series of articles, he will discuss his 
techniques for frequency management, from simple record 
keeping to custom database management and finally, the 
creation of ProScan. You can write to Perry in care of 
DataFile, P.O. Box 20111, St. Louis, Missouri, 63123 or 
through Genie BBS, address "P. Joseph." 

Scanning & monitoring the VHF-UHF spectrum can be a 
totally consuming hobby at times, but keeping track of 
hundreds or thousands of those "nameless numbers" can be 
a real chore, and a migraine headache. Well, if yours is 
a ten channel scanner, skip the rest of this article; I'd 
hate to clue you in on an obscene nightmare. 

In my early days of scanning, my monitoring pleasure was 
limited by a handful of crystals. Frequency Management, 
to me, consisted of a short list typed on a sticker stuck 
to the 10-channel radio. No problemo! 

Then I stepped up to a 200 channel programmable scanner, 
only to learn that new challenges and the obscene 
nightmare were created. Forget the sticker scheme! I 
got real smart and wrote up a tentative list, entered the 
frequencies into the radio and then typed out the final 
list while praising the Almighty for having given me the 
intestinal fortitude to take Typing 101. This, however, 
proved not to be the total solution. And the obscene 
nightmare woke me up in a cold sweat. 

Programmable scanners offer something crystal radios did 
not; the ability to reprogram the radio without having to 
open the box and change crystals. In my first year of 
owning 200 channels, I changed the frequencies a half 
dozen times or more. I edited the original frequency 
sheets by crossing out old entries and writing in new 
ones, producing a frequency list which looked more like a 
crib sheet. Eventually, I had to retype these untidy 
lists. The recurring obscene nightmare gave me insomnia. 

Aha! I plopped back down in front of the typewriter and 
concocted a blank form sheet with the necessary headers 
and column lines and then photocopied it for continual 
use. Now my mess looked organized. The list always 
looked great as long as I didn't change anything. But of 
course, changing frequencies on a scanner is about as 
synonymous as fish swimming in water. The obscene 
nightmare turned ugly. 

The advent of programmable scanners produced an anomaly. 
Trading frequency lists with other enthusiasts became the 
"in thing". Now that we didn't have to buy crystals, 
trying out new channels was as easy as punching buttons. 
The idea was to exchange each other's frequency lists and 
try to pick up on new frequencies. The anomaly occurred 
when considerable amounts of time were sucked up as I 
pored over others’ lists looking for duplicates and 
errors. Using a pencil to check off list entries was 
arcane and tedious. On top of that, it was like looking 
for a needle in a haystack to locate a specific frequency 
in a list of hundreds. My list, organized by channel no, 
made it easy to find licensee names when using the list 
with the scanner. However, when comparing my list with 
others, a lot of drudgery would have been easier if I had 
been able to sort my list, say to frequency order, to 
match the other guy's. The obscene nightmare offered no 
relief in sight. 

Then I got he 11-bent-for leather to really get organized. 

I got me a stack of 3" x 5" index cards and a card box to 
hold them all and set about to create a card for each 
channel. Each card represented a single channel and had 
detailed data including the frequency number, user name, 
type of user, etc. Making sure the channel no. appeared 
in the top corner of each card, I could easily flip 
through them to find, edit, add or delete a channel 
record. I even used tabbed dividers to partition the 
cards into sets of twenty. Although this system worked 
reasonably well, I could not reorganize the records 
without physically shuffling the cards or preparing a 
duplicate set of cards in a different order. I also did 

"THE WORLD SCANNER REPORT" (c) 1991-2; V2N3. - March, 1992; Page 3 

not like losing the benefits of a typed list. The card 
file system offered better organization but was not as 
fast as being able to scan a sheet of paper and my typing 
looks much better than my handwriting. By this time, not 
only could I see the obscene nightmare, but I began to 
taste and smell it, too. 

If it weren't for computers (and Bill Cheek showing us 
how to put thousands more channels into our scanners), I 
would probably still be using the card file system today. 
In my next column, I will tell you how I went from card 
files to computers and how the obscene nightmare was 
beaten into submission. 


By: "Professor Peabody" 

EDITOR'S NOTE: The Search & Store Modules were introduced 
as MOD-23 in Vol-1 of my Scanner Modification Handbook. 
In my opinion, the S & S Modules for the PRO-2004/5/6 by 
Key Research Co, are the next best thing to peanut butter 
& jelly. The PS-90 SEARCH & STORE module automatically 
and hands-off finds & stores into regular channel memory 
up to 255 frequencies while you're at work, asleep or on 
vacation. MOD-28, the Extended Delay Module, works in 
harmony with the Search & Store Modules by eliminating 
their greatest weakness; an occasional hangup due to very 
short signal bursts which come and go before the Search & 
Store cycle can be completed. See my SMH Vol-2 and I VSR 
V1N6P7 for the details of that potent improvement to the 
SSS modules. Now we continue as "Prof Peabody" does a 
little more hacking to his Power Search & Store Module to 
eliminate what is perhaps its only other weakness. If 
you're not acquainted with Key Research Co and their 
products, inquire to: PO Box 846; Cary, NC 27512-0846 


Hello again scanner fans! This month I bring to you a 
modification to a modification. The Key Research Co. 
POWER SEARCH & STORE module PS-90 offers unattended 
capturing & storage of up to 255 freqs and is one of the 
most effective and potent scanner mods around. It is 
very popular in the serious scanning community. I have 
one which works great, but I thought it was kind of weird 
that the PS-90 would only store 255 freqs before it 
auto-stopped. Well, this Inquiring Mind checked out the 
innards of the PS-90 and found five chips and a bunch of 
parts. Four of the chips had the markings obliterated but 
one was still readable. It's the only 16-pin chip on the 
board; a 40103 CMOS 8 bit Presettable Down Counter. The 
PS-90's 8 DIP switches preset the number of channels to 
be stored, and when the down-count hits 0, a zero detect 
signal is generated to the rest of the circuit and tells 
it to stop storing freqs. 2*-1 = 255 for you techies. 

The PS-90 module allows a maximum of 255 storage counts 
before it shuts down operation. I couldn't see the logic 
of 255 channels in a 400-channel scanner like my PRO-2005 
so I added another counter for 9 bits to permit a program 
of more than 255 channels to be stored: 2»-1 = 511 

My PRO-2005/PS-90 can now store up to 511 freqs. What? 
Only 400 channels in a block you say? Right on, but my 
circuit allows the PS-90 to be programmed for any amount 
less than 511 channels, too, including 400 exactly! The 
PS-90's operation remains the same otherwise. 

Find Pin 1 of the 16-pin 1C and then flip the board over. 
Verify Pin 1 again; then cut the trace about 1/8" away 
from Pin 1. Remove a slight bit of the trace so a cross 
connection is not made. Then fabricate the circuit shown 
in Fig-1 on a piece of perf board. If you are half good 
and know what you're doing, "dead bug" the new circuit 
right on the PS-90 board and use 30-gauge wirewrap wire 
to make the circuit connections. 

My simple circuit consists of a 4060 Counter and a 74HC00 
NAND gate connected into the PS-90 with five wires. 
Solder my 5-volt wire to Pin 16 of the 40103. Solder my 
ground wire to Pin 8 of the 40103. Solder Pin 8 of my 
74HC00 chip to an end lug of the SPDT switch. Solder a 
wire from the middle lug of the switch to Pin T of the 
40103. Solder a wire from the remaining end lug of the 
switch to the cut trace that formerly went to Pin 1 of 
the 40103. Solder a wire from Pins 1 & 2 of my 74HC00 to 
Pin 9 of the 40103. Don’t forget the 2.2-uF bypass cap 
from +5v to ground. I had problems with noise and 
glitches on the 5-volt line because there are no bypass 
caps on the PS-90 module. While you're at it, I 
recommend that you solder a 0.1-uF bypass capacitor 
directly to pins 7(-) and 14(+) of each of the other IC’s 
on the PS-90. Anything between 0.1-uF and 1.0-uF make 
good bypass caps. The SPDT switch is included so you can 
switch back to original operation anytime you wish. 

To operate the new circuit with the switch in the EXTRA 
mode, just consider it a 9th DIP switch with a value of 
256. Then program the existing DIP switches to a binary 
number of about 144. This will add up (256 + 144) to 400 
but you might want to put in a slightly lower number, say 
140, to make sure a SEARCH & STORE operation doesn't go 
past channel 400 and rewrite over the first few channels 
that were already stored. To operate the PS-90 as 
designed by the manufacturer, just put the new switch 
into the NORM mode and set the DIP switches as desired. 
And there you have it; otherwise all other functions of 
the S&S module are unchanged. Remember to observe the 
polarity of any capacitor that you install if it has 
such. Also, use minimum heat when soldering to the ICs 
and be quick about it, but don't be nervous; you’ll do 
just fine. -Prof. Peabody- 


NOTE: It is unlawful to intercept cellular telephone 
signals. Although the procedure described herein will 
restore the missing cellular bands, base and mobile, to 
the BC-855XLT, you can receive the CMT base band without 
modifiying anything by just tuning the image frequencies 
at 21.600 MHz higher than the factory-deleted ranges. On 
the BC-855XLT, the image band is 894.010 - 915.600 MHz, 
though reception might be a little fuzzy and less clear. 

"THE WORLD SCANNER REPORT" (c) 1991-2; V2N3 - March, 1992; Page 4 

Neither COtQitronics Engineering nor the “WORLD SCANNER 
REPORT" assumes responsibility for damages or other 
liability resulting from attempting to duplicate this 
procedure. It is possible that this modification may 
void your warranty. 

TOOLS NEEDED: Phillips screwdriver, wire cutters, 1/4 or 
1/2 watt resistor, 10-k, a small soldering pencil and 
small gauge, rosin core solder. 

Disconnect the power cord and with the bottom edge of the 
scanner facing you, turn it over on a soft surface to 
avoid scratching, and proceed as follows: 

1. Remove the five Phillips-head cabinet screws and 
carefully separate the cabinet. 

2. Grasp the speaker plug (not the wires), and carefully 
pull the plug from its socket. Lay the two cabinet 
halves side-by-side. 

3. Refer to Figure 2 and find the fifth jumper in a row 
at the top of the right-hand circuit board. Cut 
JV-209 at its midpoint and curl the cut ends apart so 
they can not touch anything, including each other. 

4. Solder one end of the 10-k resistor to the cathode of 

diode D201. Solder the other end of this resistor to 

the cut end of JV-209 that's closest to the center 

area of the board; do not use excessive heat. If the 
jumper comes loose from beneath the board, it will 
reattach if you hold it still as the solder cools. 

5. Plug in the A/C power cord; turn the scanner ON and 

press MANUAL : 880. : ENTER in order. If 880.000 

appears in the Display, the effort was a success; 

otherwise ERROR will be displayed as usual. The 
speaker is disconnected, so audio will not be heard. 

6. Snip off and remove excess wire from the resistor 
leads; plug the speaker connector back in place; 
reassemble the cabinet. If factory service is ever 
required, the resistor may be removed and the jumper 
lead resoldered. 

Technical Discussion: In the simplest analysis, a ground 
is connected to the CPU, IC-201 Pin 10, via jumper JV-209 
which places a 0-v (low) at Pin 10 to block the cellular 
coverage. Clip JV-209 to remove the ground and apply +5v 
(high) to Pin 10 via the isolation 10-k resistor to 
program the CPU to cover the cellular bands. The cathode 
of D-201 is a handy source of +5v. 

Referring to tne above cellular restoration procedure, 
find the jumper wire immediately to the LEFT of JV-209, 
the one that was clipped. This will be JV-208 which also 
must be clipped. Solder one end of another 10-k resistor 
to the cathode of diode D201. Solder the other end of 
this resistor to the cut end of JV-208 that's closest to 
the center area of the board; do not use excessive heat. 

Test the scanner for memory channels 51-100. Some reports 
have it that the unit will be locked up when first turned 
on after the memory mod. If so, disconnect the unit from 
all power for a short time and try again. No harm will 
come from this procedure, and if all else fails, you can 
always remove the resistor and resolder the clipped 
jumper, JV-208. Please let me know of your results, /be 



by David Moisan 

INTRODUCTION: Many shortwave listeners can't put up an 
outdoor antenna because of location, infirmity or an 
unyielding landlord. These hobbyists have few choices: a 
short random wire or an active antenna. Neither choice 
is adequate for the serious listener. Active antennas 
are expensive, apt to generate as much noise as signal, 
and are prone to overload. Random wires are cheap and 
easy, but are unpredictable performers. Both subject the 
receiver to intermod, spurious signals and other trash. 

The Carpet Loop II is an ideal upward step for the SW 
listener who wants better than a random wire but not the 
risk of an expensive dice roll for an active antenna. 
The Carpet Loop II has two components: a tuner and the 
antenna loop fashioned from 5-conductor rotator cable 
available from Radio Shack. The tuner, a giant 
L-network, couples the antenna to the radio. 

While NO antenna can give a cheap receiver sensitivity, 
selectivity, or dynamic range it never had, the Carpet 
Loop II will help you get the last ounce of performance 
from your radio. I once used a random wire which had 
severe problems with a local AM station on 1230 KHz 2-mi 
away. Intermod was all over the 9 to 12 MHz band. With 
my Carpet Loop, which then was just the cable, the nasty 
interference almost vanished and signals were stronger. I 
built the tuner later for even better results. If you’re 
an avid SWL stuck in an apartment, the Carpet Loop may be 
for you. It's cheap: maybe $25 in parts from Radio Shack 
but less if you shop around or dig through your junkbox. 
It's an excellent first project for the budding SWL. 



SI 1 pole 6 position rotary switch RS 275-1386 
I cannot swear to this procedure, but an examination of Cl 365 pf variable capacitor (see text) 
the schematic diagram suggests that 50-channels in the S2 SPST switch your choice 
BC-855XLT may have been deliberately blocked at the 01.2 1N914 silicon switching diodes RS 276-112 
factory. A pinout of the CPU shows a 100-ch memory if J]»2 6-position terminal strip RS 274-357 
Pin 9 is raised from ground to +5v. It wi 1*1 not be Misc 5-cond rotator cable (see text) RS 15-1201 

difficult to gain 50 more channels if this is correct. Metal enclosure, spade lugs, connector, coax cable 

"THE WORLD SCANNER REPORT" (c) 1991-2; V2N3 - March, 1992; Page 5 

HOW THE CARPET LOOP II WORKS: Refer to the drawings in 
Figure 3. SI, Cl, and the antenna cable connected to J1 
and J2 form a large L-network; when SI is switched 
between positions A through F, and Cl's capacitance is 
varied, the impedance of the antenna system changes. When 

51 and Cl are adjusted for best signal, the impedance 
between antenna and receiver is matched. D1 & 02 offer 
protection against static discharges and strong signals. 
The G position of SI grounds the antenna when not in use. 

52 disconnects the ground from the antenna, making the 
antenna a random wire. 

BUILDING THE TUNER : With the exception of Cl, all parts 
for the tuner are readily available from Radio Shack. 
Cl, the 365-pF variable capacitor, can be salvaged from 
an old radio or purchased from a specialty or general 
electronics supply. There are no critical parts in the 
tuner; as long as SI has at least six positions, it will 
do. D1 and D2 can be most any silicon diode. Select an 
enclosure that's big enough to comfortably install all 
the components. 

The choice for J3, the jack to the receiver, depends on 
what connector your radio uses for an external antenna. 

I used an SO-239 (RS #278-201); you could also use a TV 
antenna terminal strip (RS#274-663). 

1) Mount the components on the enclosure you'll be 
using--all wiring is point to point. I suggest 
mounting J1 and J2 on opposite sides, SI and Cl on 
top, and J3 on the other end of the enclosure. 

2) Wire SI to J1 and J2. If you use the Radio Shack 2P6T 
rotary switch, you'll be using just one of the poles. 
The diagram of the back of switch is below: 


WIRE THE TUNER AS FOLLOWS: If you use Radio Shack's 
terminal strip, you will need to drill a hole in the 
cabinet to pass the wires through from inside. Use a 
rubber grommet to keep the wires from fraying. 

SI term 


J1 term 

J1 term 


J2 term 


#1 .> 


SI ,G 




# 6 




# 7 








# 9 



J2#10 —> 




The above represents the internal wiring of the switch to 
J1 and J1 to J2. The rotator cable antenna wiring from 
J1 to J2 is shown in Figure 3 on page 8. 

3) Install and wire up Cl. Connect one terminal of Cl to 
the P terminal on SI. Connect the other end to J3. 
If using an SO-239 or phono jack, connect to the 
center conductor. If using screw terminals, connect 
to terminal #1 on J3. 

4) Connect the G terminal on SI to one lug of S-2. 
Connect the other lug of S-2 to the ground shell of J3 
or to the ground shield if coax, or to terminal #2 if 
screw terminals. 

5) Connect D1 and D2 in reverse polarity across the 
terminals of J3. 

This completes construction of the tuner. 

ANTENNA CONSTRUCTION : While other kinds of multiconductor 
cable can be used, the best for standard use is the 
5-conductor rotator cable mentioned in the parts list. 
This cable can easily withstand being stepped on; more 
importantly, the cable is easily managed and uniform in 
layout which enhances performance. It's also easier to 
wire than phone cable. 

When routing the cable, start at the receiver and go 
around the room—or the house—and back to the radio. 
Corners are easily made with this flat cable by folding 
the cable at a 90° angle, just like folding paper. 

WIRING THE CABLE TO THE TUNER: You should have the two 
ends of the cable next to the tuner. Split the wires 2-3 
inches; strip the ends and solder spade lugs on all the 
wires. With the rotator cable, mark the silver 
conductor. Connect the wire to the tuner using Figure 3. 

GROUNDING: Run a wire—preferably a large one—from the 
ground terminal on the tuner (or a mounting screw on the 
SO-239 connector if you're using one) to a suitable 
ground such as a cold water pipe; I grounded my tuner 
with a short length of RG-58 coax connected to a 
baseboard heater via an alligator clip. Connect the tuner 
to your receiver; it's ready for use! 

USING THE CARPET LOOP II : It's easier to use than to talk 
about: Tune the receiver to a desired frequency. Adjust 
SI and Cl (or the antenna trimmer on the radio) for 
strongest signal. That's it. The Carpet Loop 11 is an 
inexpensive, easily built, high performance antenna that 
can work in almost all apartments. 


No serious errors have appeared in the FATMAN computer 
interface yet, but there are a few omissions that should 
be marked on your back issues for future reference: 
V2N1P9: Mark "+5v & Pin 14" at U-10a and draw a ground at 
U-10a, Pin 7. V2N1P10: Mark "+5v" by the terminal at 
Pins 6 & 16 of U-2d. V2N2P11: Mark "+5v & Pin 14" at 
U-11 a and draw a ground at U-11 a, Pin 7. Also: Mark "+5v 
& Pin 14" at U-12a and draw a ground at U-12a, Pin 7. 
Sorry for any inconvenience caused by these omissions. 

"THE WORLD SCANNER REPORT" (c) 1991-2; V2N3 - March, 1992; Page 6 

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"THE WORLD SCANNER REPORT" (c) 1991-2; V2N2 - March, 1992; Page 7 


Please print clearly 






PHONE:( ) 



Radio Interests? (Put YEARS OF EXPERIENCE in each block that applies) 
VHF-UHF Amateur CB Shortwave Professional 



Or Occupation:_ 

List makes & models of your scanners & other radio equipment: 

Describe your technical abilities & interests; use reverse as needed. 

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Pos/t/oaj G- is /A SAFETY GROOAJb 
Pour I on E /£■ For Hi PEER FREQS, 
Positions, D, C , 8 ? A FAR E FOR. 
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"THE WORLD SCANNER REPORT" (c) 1991-2; V2N3 - March, 1992; Page 8 

PO BOX 262478 
SAN DIEGO, CA 92196-2478 




t New Computer 88S for the "I ORLD SCANNER REPORT" 4 COMMtronics Engineering 
Call (SIS) 578-924J Hidnight-6:tt am, Pacific Time ONLY 
+ PRESS RELEASE: A Cellular Telephone Monitor 
+ Economical Cellular Telephone Data Decoder 
t Scanner Frequency Management; Part I 
t Modification for the PS-90 Search & Store Module 
+ Uniden BC-855XLT Cellular Band Restoration 
- + Double the Memory Channels in the BC-855XLT? Maybe 
t Carpet Loop 11; a High Performance SWL Antenna 
t Error Corrections for FatMan Computer Interface